Microstructural evolutions in dissimilar welds between AISI 310 austenitic stainless steel and Inconel 657

This investigation has been performed to characterize dissimilar metal welds between type 310 austenitic stainless steel (SS) and Inconel 657 superalloy. The welds were produced using four types of filler materials: Inconel 82, Inconel A, Inconel 617, and type 310 SS. The weldments were characterized in detail using optical metallography and scanning electron microscopy. It can be concluded that Inconel A weld metal does not promote severe hot cracking. Continuous NbC precipitates in the Inconel 82 weld metal can sensitize the weld metal to solidification cracking. The presence of high amounts of Mo in Inconel 617 weld metal led to the formation of brittle phases. In addition, continuous precipitates were observed in the 310 SS weld metal, which can lead to poor resistance of the weld metal to hot cracking. In the aged condition, Inconel 82 and Inconel A exhibited good thermal stability, whereas Inconel 617 and type 310 SS exhibited poor thermal stability. Also, after subjecting the heat-affected zone and interface between Inconel weld metal and base metals to aging treatment, unmixed zone of Inconel 657 base metal side has disappeared. Elimination of this region can be attributed to high-temperature interdiffusion of alloying elements. Finally, it is found that Inconel A and Inconel 82 weld metals are the best choices for the dissimilar welds performed here, respectively.